Exercise‐induced stem cell activation and its implication for cardiovascular and skeletal muscle regeneration

Adult Stem Cells: Beyond Regenerative Tool, More as a Bio-Marker in Obesity and Diabetes

Obesity, diabetes, and cardiovascular diseases are increasing rapidly worldwide and it is therefore important to know the effect of exercise and medications for diabetes and obesity on adult stem cells. Adult stem cells play a major role in remodeling and tissue regeneration. In this review we will focus mainly on two adult stem/progenitor cells such as endothelial progenitor cells and mesenchymal stromal cells in relation to aerobic exercise and diabetes medications, both of which can alter the course of regeneration and tissue remodelling. These two adult precursor and stem cells are easily obtained from peripheral blood or adipose tissue depots, as the case may be and are precursors to endothelium and mesenchymal tissue (fat, bone, muscle, and cartilage). They both are key players in maintenance of cardiovascular and metabolic homeostasis and can act also as useful biomarkers.

Rehabilitation Considerations in Regenerative Medicine

Rehabilitation and regenerative medicine therapies has shown improved outcomes for tissue regeneration. Regenerative rehabilitation guides protocols regarding when to start therapy, types of stimuli administered, and graded exercise programs, taking into account biological factors and technologies designed to optimize healing potential. Although there are currently no evidence-based guidelines for rehabilitation, fundamental physical therapy principles likely apply. Immobilization tends to have deleterious effects on musculoskeletal tissues; mechanical loading promotes tissue healing and regeneration. Common physical therapy interventions may provide beneficial effects after the application of regenerative therapies. Research is needed to determine optimal rehabilitation protocols to enhance tissue healing and regeneration.

Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing

Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage.

Effect of Cellular Therapy in Progression of Becker's Muscular Dystrophy: A Case Study

Becker muscular dystrophy (BMD) is an inherited disorder due to deletions of the dystrophin gene that leads to muscle weakness. Effects of bone marrow mononuclear cell (BMMNC) transplantation in Muscular Dystrophy have shown to be safe and beneficial. We treated a 20-year-old male suffering from BMD with autologous BMMNC transplantation followed by multidisciplinary rehabilitation. He presented with muscle weakness and had difficulty in performing his activities. The BMMNCs were transplanted via intrathecal and intramuscular routes. The effects were measured on clinical and functional changes. Over 9 months, gradual improvement was noticed in muscle strength, respiratory functions and North Star Ambulatory Assessment Scale. Functional Independence Measure, Berg Balance Score, Brooke and Vignos Scale remained stable indicating halting of the progression. The case report suggests that cellular therapy combined with rehabilitation may have possibility of repairing and regenerating muscle fibers and decreasing the rate of progression of BMD.

The role of cell transplantation in modifying the course of limb girdle muscular dystrophy: a longitudinal 5-year study

Limb girdle muscular dystrophy (LGMD), a group of progressive degenerative disorders, causes functional limitation affecting the quality of life. Cell therapy is being widely explored and preliminary studies have shown beneficial effects. Cell therapy induces trophic-factors release, angiogenesis, anti-inflammation, and protein synthesis, which helps in the reparative process at the microcellular level. In this 5-year longitudinal study, the effect of autologous bone marrow mononuclear cells is studied on the natural course of 65 patients with LGMD. Functional Independence Measure and manual muscle testing showed statistically significant improvement, post-cell transplantation. The key finding of this study was demonstration of a plateau phase in the disease progression of the patients. No adverse events were noted. Autologous bone marrow mononuclear cells may be a novel, safe, and effective treatment approach to control the rate of progression of LGMD, thus improving the functional outcomes. Further randomized controlled trials are required.

A Clinical Study Shows Safety and Efficacy of Autologous Bone Marrow Mononuclear Cell Therapy to Improve Quality of Life in Muscular Dystrophy Patients

Muscular dystrophy is a genetic disorder with no definite cure. A study was carried out on 150 patients diagnosed with muscular dystrophy. These included Duchenne muscular dystrophy, limb-girdle muscular dystrophy, and Becker muscular dystrophy variants. They were administered autologous bone marrow-derived mononuclear cells intrathecally and intramuscularly at the motor points of the antigravity weak muscles followed by vigorous rehabilitation therapy. No significant adverse events were noted. Assessment after transplantation showed neurological improvements in trunk muscle strength, limb strength on manual muscle testing, gait improvements, and a favorable shift on assessment scales such as the Functional Independence Measure and the Brooke and Vignos Scales. Furthermore, imaging and electrophysiological studies also showed significant changes in selective cases. On a mean follow-up of 12 ± 1 months, overall 86.67% cases showed symptomatic and functional improvements, with six patients showing changes with respect to muscle regeneration and a decrease in fatty infiltration on musculoskeletal magnetic resonance imaging and nine showing improved muscle electrical activity on electromyography. Fifty-three percent of the cases showed an increase in trunk muscle strength, 48% showed an increase in upper limb strength, 59% showed an increase in lower limb strength, and approximately 10% showed improved gait. These data were statistically analyzed using Student's paired t test and found to be significant. The results show that this treatment is safe and efficacious and also improves the quality of life of patients having muscular dystrophy. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Biologic scaffold remodeling in a dog model of complex musculoskeletal injury

BACKGROUND

Current treatment principles for muscle injuries with volumetric loss have been largely derived from empirical observations. Differences in severity or anatomic location have determinant effects on the tissue remodeling outcome. Biologic scaffolds composed of extracellular matrix (ECM) have been successfully used to restore vascularized, innervated, and contractile skeletal muscle in animal models but limited anatomic locations have been evaluated. The aim of this study was to determine the ability of a xenogeneic ECM scaffold to restore functional skeletal muscle in a canine model of a complex quadriceps injury involving bone, tendon, and muscle.

MATERIALS AND METHODS

Sixteen dogs were subjected to unilateral resection of the distal third of the vastus lateralis and medial half of the distal third of the vastus medialis muscles including the proximal half of their associated quadriceps tendon. This defect was replaced with a biologic scaffold composed of small intestinal submucosa extracellular matrix (SIS-ECM) and the remodeling response was evaluated at 1, 2, 3, and 6 mo (N = 4 per group).

RESULTS

The initial remodeling process followed a similar pattern to other studies of ECM-mediated muscle repair with rapid vascularization and migration of myoblasts into the defect site. However, over time the remodeling response resulted in the formation of dense collagenous tissue with islands of muscle in the segments of the scaffold not in contact with bone, and foci of bone and cartilage in the segments that were adjacent to the underlying bone.

CONCLUSIONS

SIS-ECM was not successful at restoring functional muscle tissue in this model. However, the results also suggest that SIS-ECM may have potential to promote integration of soft and boney tissues when implanted in close apposition to bone.

Combined intermittent hypoxia and surface muscle electrostimulation as a method to increase peripheral blood progenitor cell concentration

Background

Our goal was to determine whether short-term intermittent hypoxia exposure, at a level well tolerated by healthy humans and previously shown by our group to increase EPO and erythropoiesis, could mobilize hematopoietic stem cells (HSC) and increase their presence in peripheral circulation.

Methods

Four healthy male subjects were subjected to three different protocols: one with only a hypoxic stimulus (OH), another with a hypoxic stimulus plus muscle electrostimulation (HME) and the third with only muscle electrostimulation (OME). Intermittent hypobaric hypoxia exposure consisted of only three sessions of three hours at barometric pressure 540 hPa (equivalent to an altitude of 5000 m) for three consecutive days, whereas muscular electrostimulation was performed in two separate periods of 25 min in each session. Blood samples were obtained from an antecubital vein on three consecutive days immediately before the experiment and 24 h, 48 h, 4 days and 7 days after the last day of hypoxic exposure.

Results

There was a clear increase in the number of circulating CD34+ cells after combined hypobaric hypoxia and muscular electrostimulation. This response was not observed after the isolated application of the same stimuli.

Conclusion

Our results open a new application field for hypobaric systems as a way to increase efficiency in peripheral HSC collection.